Abrading implement



Nov. 27, 1956 A. FIELD 2,771,722

ABRADING IMPLEMENT Filed Dec. 13, 1954 INVENTOR fla /=7- A7540 ABRADlNGIMPLEMENT Albert Field, Dayton, Uhio Application December 13, 1954,Serial No. 474,669

2 Claims. (Cl. 51l95) This invention relates to abrading implements andparticularly to abrasive coated flexible sanding and like discs whichare mounted on a mandrel for application to the work, the mandrel inturn being installed in a rotary hand-held power tool or the like.

It has heretofore been proposed to embody in such discs a hollowinternally threaded metal grommet having the dual function of holdingthe several plies of the sanding disc in assembled relation, in the caseof a multiply disc, and also of enabling a positive driving engagementof the disc with the mandrel without the use of bolts and separablenuts, the mandrel having a threaded tip which is received in theinterior of the grommet. The disc is composed essentially of a fabricmaterial and while it fits relatively closely upon the grommet it hasbeen possible for the ferrule to turn relatively to the disc,particularly under high speed operation and upon the imposition ofrelatively high resistance to rotation of the disc.

It is the object of the invention to obviate slipping of the disc andgrommet relatively to one another, and it is an attendant object in thisconnection to prevent such slipping without the use of accessory deviceswhich would add to the complication and cost of the disc assembly.

In the drawing,

Fig. 1 is a view in side elevation of a disc and mandrel assembly,showing the disc mounted on the mandrel;

Fig. 2 is a view in front elevation of a sanding disc in accordance withthe illustrated embodiment of the invention;

Fig. 3 is a detail fragmentary view of the disc of Fig. 2 inlongitudinal section; and

Fig. 4 is a detail fragmentary view taken substantially along the line4-4 of Fig. 3.

Referring to the drawings, an abnading implement in accordance with theinstant illustrated embodiment of the invention comprises a disc made upof multiple superposed plies of a fabric material coated with anabrasive, and the several plies may be cemented together to define aunitary disc construction. A plurality of cuts 11 and .12 may be formedin some or all of the plies 'of the disc for greater flexibility in theperipheral area. The disc has a central through opening 13.

Installed in the opening 13 is a grommet 14 having a cylindrical portion15 in contact with the wall of the opening 13, and further having at oneend thereof a flange .16 lying outside the opening 13 and turned overupon the body oi the disc 10. At its opposite end the grommet extendsoutside the opening .13 and terminates 2 in a relatively large annularhead portion 17. The disc 10 is clamped between the end portions 16 and1-7 of the grommet by upsetting the end 16 substantially to the positionshown.

The interior of the grommet 14 is threaded in a manner to receive athreaded tip 18 on a mandrel 1 9. The tip 18 projects from a relativelylarge diameter shoulder 21 :at the base of the mandrel 19, whichshoulder abuts the end portion 16 of the grommet, and the surface of thedisc, in a way to complement or to oppose the large head portion 17 ofthe grommet. Themandrel 1 9, as may be seen in Fig. 1, further includesa shank portion '22 for reception in the chuck of .a power tool.

The enlarged head portion 17 has a circumferential series of cut outportions 23 in its periphery, each such portion being substantiallycrescent-like in shape and defining sharp edges 24. Under compressiveinfluences applied in installing the grommet 17, and in response torelative rotation between the disc and grommet, the edges 24 tend toim-bed themselves into the fabric of the disc. The disc and grommet arethereby in effect locked together for unison rotation. It will beunderstood that the disc :10 is rotated by virtue of its mounting on themandrel 19, the mandrel rota-ting relatively to the disc until the tip 18 penetrates fully into the grommet 17 and until the shoulder 21 seatson the end 16 of the grommet and on the disc. When this occurs,continued rotary motion of the mandrel is partaken of by the grommet,and, by virtue of the gripping connection above described, by the disc10 as well. 'It will further be noted that the edges 24 are arranged toimbed themselves in the fabric of the disc in either direction ofrotation so that should the direction of rotation of the mandrel bereversed, as to withdraw the mandrel from the grommet, the ferrule willbe precluded from following the motion of the mandrel relatively to thedisc.

What is calime'd is:

1. An 'abrading implement, including a multiply disc made up of anabrasive coated fabric material, :an internally threaded grommetinstalled in said disc holding said plies is superposed contactingrelation, one end of said grommet having a planar surface inapproximately parallel contacting relation to the exposed surface of aterminal one of the superposed plies and the interior of said grommetbeing open to receive the threaded end of a mandrel whereby to supportand to rotate said disc, and cut-outs in the periphery of said one endof the grommet opening through said planar surface to define therewithsharp edges tending to imbed themselves in the fabric of said one ply inresponse to relative rotation of said grommet and disc.

2. An a-brading implement according to claim 1, characterized in thatsaid cut-outs are approximately crescentlike in shape, the walls ofwhich are inclined outwardly from the opposite end of the grommet to thesaid one end thereof to define with said planar surface the said sharpedges.

References Cited in the file of this patent UNITED STATES PATENTS

